This chapter reviews and discusses various aspects of texture analysis. The concentration is o the various methods of extracting textural features from images. The geometric, random field, fractal, and signal processing models of texture are presented. The major classes of texture processing pro lems such as segmentation, classification, and shape from texture are discussed. The possible applic tion areas of texture such as automated inspection, document processing, and remote sensing a summarized. A bibliography is provided at the end for further reading.

Texture analysis

References.- 1 Solubility of Proteins.- 1.1 Introduction.- 1.1.1 Factors Affecting Solubility of Proteins.- 1.2 Solubility of Meat and Fish Proteins.- 1.2.1 Solubility of Muscle Proteins.- 1.2.2 Solubility of Stroma Proteins.- 1.2.3 Protein Solubility in Processed Meats.- 1.2.4 Solubility of Blood Proteins.- 1.2.5 The Effect of Heating on Solubility of Proteins.- 1.2.6 The Effect of Freezing and Storage When Frozen on Protein Solubility.- 1.2.7 The Effect of Protein Modification and Irradiation Treatment.- 1.3 Solubility of Milk Proteins.- 1.4 Solubility of Egg Proteins.- 1.5 Solubility of Plant Proteins.- 1.5.1 Soybean Proteins.- 1.5.2 Peanut Proteins.- 1.5.3 Pea and Bean Proteins.- 1.5.4 Sunflower Proteins.- 1.5.5 Corn Proteins.- 1.5.6 Miscellaneous Plant Proteins.- References.- 2 Water Holding Capacity of Proteins.- 2.1 Introduction.- 2.2 The Mechanism of Protein-Water Interaction.- 2.2.1 Factors Influencing Water Binding of Proteins.- 2.3 Water Holding Capacity of Proteins in Meat and Meat Products.- 2.3.1 Water Binding Capacity of Muscle Proteins.- 2.3.2 Factors Influencing Water Binding of Muscle Proteins.- 2.3.3 Water Binding in Comminuted Meat Products.- 2.3.4 Milk Proteins in Comminuted Meats.- 2.3.5 Soy Proteins in Comminuted Meats.- 2.3.6 Corn Germ Protein in Comminuted Meats.- 2.4 Water Holding Capacity of Milk Proteins.- 2.5 Water Holding Capacity of Egg Proteins.- 2.6 Water Holding Capacity of Plant Proteins.- 2.6.1 Soybean Proteins.- 2.6.2 Pea and Bean Proteins.- 2.6.3 Sunflower Proteins.- 2.6.4 Corn Proteins.- 2.6.5 Wheat Proteins.- 2.6.6 Miscellaneous Proteins.- References.- 3 Emulsifying Properties of Proteins.- 3.1 Introduction.- 3.2 Hydrophobic and Hydrophilic Properties of Proteins.- 3.3 Interfacial Film Formation and Properties.- 3.4 Factors Affecting the Emulsifying Properties of Proteins.- 3.4.1 Protein Concentration.- 3.4.2 pH of Medium.- 3.4.3 Ionic Strength.- 3.4.4 Heat Treatment and Other Factors.- 3.5 Emulsion Stability.- 3.6 Measuring Emulsifying Properties.- 3.7 Emulsifying Properties of Meat Proteins and Proteins Utilized as Extenders in Meat Products.- 3.7.1 Protein Functionality in Comminuted Meats.- 3.7.2 Emulsifying Properties of Various Muscular Proteins.- 3.7.3 Emulsifying Properties of Blood Proteins.- 3.8 Functionality of Nonmeat Proteins in Comminuted Meats.- 3.8.1 Milk Proteins.- 3.8.2 Soy Proteins.- 3.8.3 Corn and Wheat Germ Proteins.- 3.9 Milk Proteins as Emulsifiers in Food Systems.- 3.9.1 Emulsifying Properties of Caseins and Caseinates.- 3.9.2 Emulsifying Properties of Whey Proteins.- 3.10 Emulsifying Properties of Egg Proteins.- 3.11 Emulsifying Properties of Plant Proteins.- 3.11.1 Soybean Proteins.- 3.11.2 Pea and Bean Proteins.- 3.11.3 Corn Proteins.- 3.11.4 Miscellaneous Proteins.- References.- 4 Oil and Fat Binding Properties Of Proteins.- 4.1 Introduction.- 4.2 Fat Binding Properties of Proteins of Animal Origin.- 4.2.1 Muscle Proteins.- 4.2.2 Soy Proteins in Comminuted Meats.- 4.2.3 The Effect of Corn Germ Protein Flour on Fat Binding in Ground Beef Patties.- 4.2.4 Milk and Egg Proteins.- 4.3 Fat Binding Properties of Proteins of Plant Origin.- 4.3.1 Soy Proteins.- 4.3.2 Pea, Bean and Guar Proteins.- 4.3.3 Corn Germ Proteins.- 4.3.4 Wheat Proteins.- 4.3.5 Cottonseed Proteins.- 4.3.6 Miscellaneous Proteins.- References.- 5 Foaming Properties of Proteins.- 5.1 Introduction.- 5.2 The Mechanism of Foam Formation.- 5.2.1 Factors Affecting Foam Formation.- 5.2.2 Foam Stability.- 5.3 Milk Proteins.- 5.3.1 Factors Affecting the Foaming Properties of Milk Proteins.- 5.4 Egg Proteins.- 5.4.1 The Effect of Processing on Foaming Properties of Egg Proteins.- 5.5 Blood Proteins and Gelatin.- 5.6 The Foaming Properties of Plant Proteins.- References.- 6 Gelling Properties of Proteins.- 6.1 Introduction.- 6.2 The Mechanism of Protein Gel Formation.- 6.2.1 Heat-Induced Gelation.- 6.2.2 Protein-Water Interaction in Gels.- 6.2.3 Factors Affecting the Properties of Gels.- 6.3 Gelling Properties of Meat Proteins.- 6.3.1 Myofibrillar Proteins.- 6.3.2 Sarcoplasmic Proteins.- 6.3.3 Gelation of Red and White Muscle Proteins.- 6.3.4 Factors Affecting the Gelling Properties of Meat Proteins.- 6.3.5 Myosin Blends with Other Proteins and Lipids.- 6.3.6 Fish Proteins.- 6.3.7 Collagen Gelation.- 6.3.8 Blood Proteins.- 6.4 Gelling Properties of Milk Proteins.- 6.4.1 Gelling Properties of Whey Protein Concentrate, Isolate, and Individual hey Proteins.- 6.4.2 The Effect of Heating and Protein Concentration.- 6.4.3 Gelation of Casein.- 6.4.4 Factors Affecting the Gelling Properties of Milk Proteins.- 6.5 Gelling Properties of Egg Proteins.- 6.5.1 Gelation of Egg White.- 6.5.2 Gelation of Yolk.- 6.6 Gelling Properties of Soy Proteins.- References.

Functionality of Proteins in Food

Mycotoxin contamination of the feed supply chain: Implications for animal productivity and feed security

During the last ten years significant progress has been made in the understanding of specific ion effects. On the one hand new ideas about the origin of these effects came up, and on the other hand new experimental techniques were developed so that now even the ion concentration profile near surfaces can be measured with some confidence. In the present review some of the most important new progresses are summarised and critically discussed, especially in the context of colloidal and biological systems.

Specific ion effects in colloidal and biological systems

Ochratoxin A (OA) is a toxin that contains an isocoumarin moiety linked by a peptide bond to phenylalanine. It is produced by certain Penicillium (mainly P. verrucosum) and Aspergillus (mainly A. alutaceus) species of storage fungi. Total amounts of OA and other related toxins produced by these fungi are influenced by many factors. Several forms of OA have been discovered, some of which are highly toxic, whereas others have lower toxicity. Ochratoxin A has been detected in foods, feeds, animal tissues, and human blood in both Europe and North America. It has been implicated in the fatal human disease Balkan endemic nephropathy, has been shown to be a powerful carcinogen in rodents, and produces many other adverse effects in animals. It is absorbed passively throughout the gastrointestinal tract and in an active manner in the kidney. It is subjected to intestinal secretion and reabsorption via enterohepatic recycling. Binding of OA in the blood to the albumin fraction and recycling in the bile and kidney contributes to its long half-life in animals. Ochratoxin A is hydrolyzed to its nontoxic alpha form (O alpha) by microorganisms in the rumen, cecum, and large intestine. The toxin is excreted primarily in the urine as O alpha and to a lesser degree as OA; smaller amounts of OA and O alpha are generally excreted in the feces. Three distinct mechanisms of OA toxicity have been proposed; other toxic effects of OA seem to be secondary in nature. Several different strategies can be employed for controlling or neutralizing the effect of OA, including the use of proper storage conditions, the use of specific adsorbents to reduce absorption of OA, and the feeding OA-contaminated feedstuffs to ruminants. Antioxidants such as ascorbic acid have been shown to reduce the toxic effects of OA in laying hens. In summary, OA contamination of cereal food and feed may occur, given appropriate conditions. Implementation of suitable procedures may eliminate or minimize this potentially serious problem.

A review of recent advances in understanding ochratoxicosis.

Sols were prepared from comminuted fish (surimi), beef, pork and turkey muscles. Continuous evaluation of changes in structural rigidity and energy damping during heating of the sols from 3° to 95°C was performed in a nondestructive, temperature-controlled Thermal Scanning Rigidity Monitor. Surimi presented major rigidity transitions at 40°. 48° and 65°C; beef at 43°. 56° and 69°C; pork at 44°, 53° and 69°C; and turkey at 50°, 53° and 79°C. All materials exhibited rapid decrease in energy damping (i.e. increase in elasticity) over a short temperature span. Failure testing of gels indicated differences in strength and deformability. SEM micrographs provided an insight into structural features of the gels.

Thermally Induced Gelation of Selected Comminuted Muscle Systems–Rheological Changes during Processing, Final Strengths and Microstructure

The textural attributes of 8 different heat-induced protein gel preparations evaluated by torsion failure testing and Instron texture profile analysis (TPA) were compared to sensory ratings by a trained texture profile panel. The gels presented a wide range of textural properties as determined by the instrumental and sensory parameters. Among the instrumental parameters, true shear strain at failure was the most frequent and significant predictor of sensory notes. Initial shear modulus and 50% compression force had the poorest correlations with sensory notes. Comparison of the two instrumental tests produced high correlations between shear stress at failure and TPA hardness; true shear strain at failure and TPA cohesiveness; and, initial shear modulus and 50% compression force. High correlations were also observed among various panel notes. Canonical correlation analyses showed that sets of linear combinations of parameters from each one of the 3 tests (torsion, TPA or sensory) were highly correlated to sets from either of the other two. Regression equations relating each of the instrumental tests to sensory notes were developed. Of the torsion failure parameters, the logarithm of true shear strain most commonly appeared in the equations. Of the TPA parameters, cohesiveness and its logarithm were the terms that were most frequent. High R2 values were obtained for regression equations developed for predicting torsion failure parameters based on TPA parameters.

Comparison of two instrumental methods with sensory texture of protein gels

Myosin heavy chain (MHC) content of cooked gels of pollock and croaker surimi decreased during preincubation (“setting”) at temperatures ranging from 4–50C. Decreases in MHC content were attributed to either nondisulfide covalent cross-linking or proteolysis. Depending upon which process dominated at a given temperature, formation of stronger or weaker gels occurred, respectively. Maximum production of cross-linked polymers occurred at the optimum setting temperatures, i.e., at 25C for pollock surimi and 40C for croaker surimi. Subsequent cooking of these set gels at 90C decreased the amount of cross-linked polymers formed at the optimum setting temperature. Addition of free lysine-HCl inhibited formation of cross-linked polymers of MHC during setting and the increase in cooked gel strength for both species. This supports published evidence that cross-linking of MHC during setting may be of the e-amino-(γ-glutamyl) lysine I type, mediated by a transglutaminase enzyme.

Nondisulfide covalent cross-linking of myosin heavy chain in "setting" of Alaska pollock and Atlantic croaker surimi

A torsion test was developed for studying the structural failure of selected raw fruits and vegetables. Apple, melon and raw potato flesh were tested at a shear strain rate of approximately 0.26s-1 in torsion and uniaxial compression. Low strain modulus values were determined in addition to shear stresses and normal strains at failure.



Results corroborated the maximum normal strain failure criterion proposed by Segerlind and Dal Fabbro (1978) for apples and suggested its application to potatoes and melons if true strains are used rather than engineering strains. The maximum shear stress theory also seemed to be a possible failure criterion for potatoes. Results comparing compressible and incompressible materials suggest that bulk strain affects the shear stress at failure. The observed failure planes supported the quantitative results for stresses at failure. Scanning electron micrographs indicated that the cellular failure occurred in the cell wall, regardless of whether it was due to tension,



Varying specimen lengths or diameters had negligible effects on the uniaxial compression modulus but did affect the shear stress at failure in a manner yet to be satisfactorily explained.

Structural failure in selected raw fruits and vegetables

The effects of beef plasma hydrolysate and egg white solids were evaluated in surimi gels using measurements of torsional shear stress and strain, bound water, cook loss and SDS-PAGE. Treatments included level of protein addition, surimi type (by species and grade) and cooking schedule. Addition of proteins, regardless of type or level of addition, significantly increased torsional shear stress and strain for all gels precooked at 60°C (90°C final cook). For gels made from low quality surimi, all levels of treatment proteins improved stress and strain for all cooking schedules and improved water holding for gels precooked at 60°C. Electrophoretic results showed a decrease in the density of the myosin heavy chain only in those gels without added proteins precooked at 60°C.

Donald D. Hamann

Papers

Thermally Induced Gelation of Selected Comminuted Muscle Systems–Rheological Changes during Processing, Final Strengths and Microstructure

Comparison of two instrumental methods with sensory texture of protein gels

Nondisulfide covalent cross-linking of myosin heavy chain in "setting" of Alaska pollock and Atlantic croaker surimi

Structural failure in selected raw fruits and vegetables

Inhibition of Modori (Gel Weakening) in Surimi by Plasma Hydrolysate and Egg White